Dual Frequency ESA Radar Scan Range Extension
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Solution Overview
Problem
Conventional active electronically scanned array (AESA) radar systems face limitations in scan range due to beam broadening at extreme angles, leading to scan loss and increased size, weight, power, and cost when attempting to expand scan range through increased antenna elements or multiple AESAs.
Innovation Solution
Operating a single AESA radar system at two distinct frequencies to create a faux planar aperture, allowing for wider scan ranges without adjusting amplitude or phase values, and relaxing antenna element spacing to reduce the number of elements required while maintaining scan coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the number of antenna elements in the phased array is increased to expand scan range, then the scan range is improved, but the size, weight, power consumption, and cost of the AESA system increase prohibitively
Solution Approach 1:
The patent changes the operating frequency parameter of the AESA system to achieve extended scan coverage. By operating at two distinct frequencies (first and second frequencies), the system creates different effective apertures that enable scanning beyond the conventional scan range without adding more antenna elements. This frequency-based parameter change allows the same physical array to provide wider coverage while maintaining the original system size and weight.
2Device complexity
If antenna element spacing is increased to reduce the number of elements, then cost and complexity are reduced, but grating lobes are created that degrade scan performance
Solution Approach 1:
The patent utilizes frequency parameter changes to mitigate grating lobe effects. By operating at two distinct frequencies, the system creates effective apertures where the grating lobes that would normally degrade performance at wide scan angles are pushed to different angular positions. This allows the system to use larger element spacing (reducing element count) while maintaining scan performance through frequency-based compensation.
Solution Approach 2:
The patent employs periodic switching between two distinct operating frequencies. The system alternates between transmitting and receiving at the first frequency and the second frequency, creating a periodic operation pattern. This periodic frequency switching allows the system to exploit the different spatial characteristics at each frequency, effectively managing grating lobe placement and maintaining reliable scan performance across an extended angular range.
3Area of moving object
If multiple AESAs are utilized to increase scan range, then coverage is improved, but the size, weight, power, and cost of the system increase prohibitively
Solution Approach 1:
The patent makes a single AESA system multi-functional by enabling it to operate at two distinct frequencies with different effective aperture orientations. This allows one AESA to perform the function that would otherwise require multiple AESAs, providing extended scan coverage while consuming the power of a single system. The same antenna elements serve multiple scanning purposes by switching between frequencies, eliminating the need for additional hardware and reducing overall system cost.
Data Source
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AI summary
Systems and methods described herein are directed towards a radar system and a dual frequency electronically scanned array (ESA) capable of transmitting and receiving radio frequency (RF) signals at least two frequencies. The ESA includes a plurality of antenna elements which form a first effective aperture at a first radio frequency (RF) frequency and operational over a first scan range and which form a second effective aperture at a second radio frequency (RF) frequency and operational over a second scan angle. The first and second scan ranges are complementary so as to provide the radar system having an overall scan range. The plurality of antenna elements are spaced apart from each other by an amount related to at least one of the first and second scan ranges and/or one or more operating frequencies of the radar system.